Other OSHA Regulations
Altogether, OSHA has
established about 500 PELs (permissible exposure limits)
that regulate the exposure of workers to hazardous air
contaminants, including elements, compounds (especially
organic) and mineral dusts. In the plating and metal
finishing industry, the most significant PELs are those for
Cr6+, Cr3+ and cadmium.
Trivalent chromium
US OSHA PELs
Cr2+ 500 µg m-3 (as
Cr, 8-hour TWA)
Cr3+ 500 µg m-3 (as
Cr, 8-hour TWA)
Cr6+ 52 µg m-3 (as
Cr, 8-hour TWA)
Trivalent chromium (Cr3+) is widely considered to be much less toxic than
Cr6+ and, in the US, is regarded as no more toxic
than metallic chrome. However, in Europe it is regarded as
more harmful than the metal, which suggests that Cr3+
may well become as highly regulated as Cr6+ in
the long term. Denmark already classifies Cr3+
as a restricted substance, a designation that means its use
is allowed but alternatives are preferred. In the US, the
OSHA PEL for both Cr2+ and Cr3+ is
currently 500 µg m-3 (as Cr, 8-hour time-weighted
average) – considerably higher than the new value for
hexavalent chromium.
Cadmium
Cd 5 µg m-3
(8-hour TWA)
Cadmium
is a very toxic heavy metal that
is on the EPA’s Toxic 17 list. Because it is
hazardous to both workers and consumers as well as the
environment, the use of cadmium has been regulated in the US
and elsewhere for many years. Cadmium electroplating, once
used extensively on consumer products and automotive
fasteners, is now largely restricted to aerospace
applications, and even in this area several cleaner
alternatives have been developed. Besides plating,
industrial processes that involve cadmium include some types
of welding, nickel-cadmium battery manufacturing and dry
color formulation.
The 8-hour time-weighted
average PEL for cadmium and its compounds, including dust
and fumes, is 5 µg m-3. For a small number of
industries, OSHA has also established SECALs (separate
engineering control air limits) for cadmium of either 15 µg
m-3 or 50 µg m-3 as the lowest
feasible levels above the PEL that can be achieved by
engineering and work practice controls. Among the
requirements of the cadmium rule are that employees should
be prohibited from eating and drinking in regulated areas.
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